Physiological Entomology最新文献

The grain chinch bug (Macchiademus diplopterus Distant) is a phytosanitary pest, endemic to the Western Cape in South Africa. At the start of the aestivation phase of their lifecycle, grain chinch bugs seek sheltering sites, which potentially include fruit and fruit trees if orchards are near host plants. Aestivating grain chinch bug on export fruit is considered contaminant or hitchhiker phytosanitary pests. Previous studies have indicated that the grain chinch bug has the ability to become more tolerant of thermal stresses as they progress through their aestivation cycle. To examine the potential physiological changes that occur during aestivation, molecular (soluble protein identification) and biochemical (macromolecule) analyses were performed on the insects before entering aestivation, as well as early, mid, mid-late and late aestivation periods. Analyses provided useful information on the abundance and identity of individual soluble proteins and concentration of macromolecules, indicating whether compounds are up- or down-regulated throughout the aestivation cycle. The focus of this investigation was to examine the influence of heat shock proteins and proteins involved in energy production and metabolism throughout the aestivation period. Results provide insight into the thermo-tolerance capabilities or mechanisms of the grain chinch bug. The significant decrease in the number of individual proteins identified in samples before aestivation compared to early aestivation indicated the insects' progression into a hypometabolic state. During the early, mid and mid-late aestivation periods (from December to May), large volumes of fruit are exported from South Africa. An increase in abundance of proteins, such as smHsp20, Hsp10, 70, 80 and 90, occurred during the mid/mid-late aestivation period compared with the early period. This indicated the potential role of heat shock proteins in the insect's ability to increase its thermo-tolerance at a later stage within the aestivation cycle.

The study of insect flight is important for conservation and sustainability efforts, as predicting insect dispersal can aid management programmes in tackling economic and ecological harm from, for example, invasive species. Flight mills are invaluable tools for measuring the factors of insect flight under laboratory conditions, as they lower several technical and financial barriers to conduct experiments. It is especially difficult, however, to make assumptions about the energetic cost of tethered flights conducted using different tethers, or even on different flight mills, due to the mechanical variability of the bearing friction and air resistance of the rotating assembly. This additional uncertainty necessitates a larger number of replicates for any given standard of statistical confidence. By characterising flight mill friction, this uncertainty can both be reduced in magnitude and assigned a specific, well-defined numerical value. We present a simple methodology to characterise this friction through dynamic calibration of the flight mill, at a high statistical confidence. This study uses videography of a flight mill undergoing free velocity decay due to friction, using an in-house developed software to extract angular velocity from video data. However, the technique is readily adaptable to other measurement techniques. Using the velocity, alongside the mass moment of inertia of the flight mill, allows us to determine the rotational friction coefficient. This friction coefficient provides precise measurements of thrust production, and therefore the energy expenditure of flight, by the tethered insect.

Bombyx mori Linnaeus, 1758 (Lepidoptera: Bombycidae), a very important economical insect and backbone of the silk industry, is fully reliant on humans for its life cycle. It has short life span, possessing many genes having high degree of homology with human disease-causing genes, low breeding and maintenance cost, has less ethical issues associated with it and has also got its genome fully sequenced. Because of these characteristics, it has been recognized as an alternate invertebrate model organism candidate for use in life science research. It has been successfully used as an alternative invertebrate model organism in a variety of scientific domains, including human disease models, environmental monitoring models, epigenetic models and microbial drug screening and discovery models, since the last decade. This newly emerged model has given promising results so far in its short journey and has a tremendous future prospect of establishing itself as a successful model just like the classical invertebrate models, Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae) and Caenorhabditis elegans Maupas, 1900 (Rhabditida: Rhabditidae). The use of the silkworm B. mori as a model organism in areas linked to human health and disease is reviewed here.

The present research investigates host preferences and larval development of the melon ladybird Chnootriba elaterii (Rossi) (Coleoptera: Coccinellidae), considering seven Cucurbitaceae plant species (Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita pepo, Cucurbita moschata, Lagenaria siceraria and Luffa aegyptiaca), to determine whether mother host preference is related with larval performance. The damaged area on plant leaves due to insect feeding in dual-choice experiments was used to evaluate food preferences. Behavioural experiments in a Y-tube olfactometer tested the role of olfaction in host-plant selection. Parameters such as development duration and morphometric characters of emerged adults were evaluated to estimate larval performance. Adult females selected watermelon and melon as their favourite food while firmly refusing loofah and calabash. Insects preferred melon over watermelon, but the larval development on melon was slower; moreover, watermelon allowed larvae to develop faster than other tested plants, while loofah did not allow larval development. Larvae fed and developed on melon, pumpkin, zucchini, cucumber and calabash, without strong differences. These results only partially supported the preference-performance hypothesis suggesting that it could be context dependent. Contrary to expectation, volatile organic compounds (VOCs) belonging to the host, only partially could guide adult females in the olfactometer. This result suggests that long-distance olfactory stimuli alone cannot provide sufficient information for host-plant selection in melon ladybirds. Considering the economic relevance of C. elaterii, the results of the present paper answer some basic questions about host-plant selection for this pest insect, potentially useful to improve control strategies in crops.

Flower nectar, a sugar-rich solution containing amino acids as major secondary solutes, is the primary energy source for bees. Proline is one of the most abundant protein nectar amino acids, showing several effects on bee physiology. Mason bees are outstanding pollinators, often preferred to Apis mellifera for pollination of fruit trees. Among them, Osmia cornuta (Latreille) is one of the most successfully managed species on a commercial scale. In this work, the effects of 10 mM proline-enriched diet administration on O. cornuta feed consumption, survival, behaviour and haemolymph amino acid composition were investigated. Feed intake was higher for the proline diet, while survival rate was not affected. Behaviour was affected only in the senescence of the mason bees with a reduction in locomotor activity induced by proline intake. Proline diet also affected the haemolymph amino acid composition, decreasing concentration of tyrosine, methionine, leucine and phenylalanine after 10 days of feeding. These results were discussed in relation to the potential involvement of proline in oxidative stress in insects and proline's ability to be converted to other amino acids. Further investigations are necessary to better understand the molecular mechanisms of proline effects on locomotion and oxidative stress.

Recently, neuropeptide F2 (NPF2) has been demonstrated to increase food consumption and body weight in the cotton bollworm, Helicoverpa armigera. This study evaluated the effect of NPF2 on the adult female reproductive system of H. armigera. Daily NPF2 injections increased oocyte size, ecdysteroid titre in ovaries and haemolymph and the expression level of ecdysone receptor (EcR), ultraspiracle (USP) and vitellogenin (Vg) genes. However, NPF2 injection had no effect on the expression level of hormone receptor 3 (HR3). Fecundity and fertility were increased after the injection of NPF2. The knockdown of the NPF2 gene using RNA interference (RNAi) had opposite effects compared to NPF2 injection. Overall, these results revealed that NPF2 has a regulatory role in the female reproduction of the cotton bollworm.

Acetylcholinesterase (AChE) is a promising enzyme and a biomarker to monitor the physiological status of honey bees. To gain a basic understanding of AChE in bees, we measured AChE activity in the head tissue of forager honey bees belonging to Apis cerana, Apis mellifera, and Apis dorsata collected from five districts of Nepal during pre-winter and winter seasons. We estimated AChE-tissue activity (μmol/min/g head tissue) and AChE-specific activity (μmol/min/mg protein) using Ellman assay kit and protein concentration (mg/g head tissue) using Lowry assay method. A significant increase in all three parameters was observed in winter A. cerana and varied between species indicating differences in physiological resistance and responses to various environmental changes between native (A. cerana and A. dorsata) and non-native (A. mellifera) bees. Overall, AChE-tissue and specific activities were positively correlated and, as expected, AChE-specific activity was negatively correlated with the protein concentration.